1. Technical Field
Exemplary embodiments of the present invention relate to a method of supplying power, a power supply apparatus for performing the method and a display apparatus having the apparatus. More particularly, exemplary embodiments of the present invention relate to a method of supplying power for reducing power loss, a power supply apparatus for performing the method and a display apparatus having the apparatus.
2. Discussion of Related Art
A liquid crystal display apparatus may include a display panel, which displays images using the light transmittance of liquid crystal molecules, and a backlight assembly disposed under the display panel to provide the display panel with light.
The display panel may include an array substrate, a color filter substrate and a liquid crystal layer interposed between the array substrate and the color filter. The array substrate may include a plurality of pixel electrodes and a plurality of thin-film transistors (TFTs) electrically connected to the pixel electrodes. The color filter substrate may include a common electrode and a plurality of color filters.
When an electric field is applied to the liquid crystal layer, the arrangement direction of the liquid crystal molecules of the liquid crystal layer is changed so that the light transmittance is changed. For example, when the light transmittance is increased to a maximum value, the display panel realizes a white image having a high luminance. However, when the light transmittance is decreased to a minimum value, the display panel realizes a black image having a low luminance.
The backlight assembly may include an inverter. The inverter converts a direct current (DC) voltage into an alternating current (AC) voltage. The DC voltage is applied to the backlight assembly according to a brightness control voltage from an external device. An inverter controller included in the inverter turns on a light source by providing the light source with the converted AC voltage and controls the brightness of the light source. The DC voltage may be provided from a power supply apparatus included in the display apparatus.
The power supply apparatus receives an AC voltage from an external AC input part to provide the DC voltage to the inverter and the display panel. However, a power factor at an input part receiving the AC voltage decreases when the power supply apparatus converts the AC voltage to the DC voltage by using a capacitor input type rectifier. Additionally, power loss is caused by switching operations of switching elements in the power supply apparatus.
Thus, there is a need for a method of supplying power to improve a power factor and reduce power loss, a power supply apparatus for performing the method, and a display apparatus having the power supply apparatus.